Many tissue specific collagens have been described in the last several years (I,II,III,IV, X2Y, B2A, CP45, etc.). Their functional significance at the molecular level is not understood, although some hints in this respect have been gathered based on their tissue distribution. Disease processes are known to alter the normal balance between collagen types. The area which we believe has most physiological significance is that relevant to the modulation of biosynthesis and turnover. Earlier work using cartilage cells has shown that chondrocytes lose their initial phenotype quite rapidly in culture. In organ culture this does not occur. Animal studies, which involves inducing lesions in cartilage and bone, are proposed as an extension of these findings. Osteocyte cultures will be established, and the phenotype of these cells as they lay down a calcifiable matrix will be investigated. These studies will be adapted to investigate Osteogenesis Imperfecta. Serum factors will be investigated for their effects on collagen synthesis (by analogy to experiments we have completed in Pre-tibial-myxedema which suggests that fibroblasts may be "tissue specific"). Modulation of collagen synthesis by smooth muscles cells (veins arteries, and transposed vessels will be investigated. Kidney tubule basement membrane shall be isolated and characterized to provide a standard for Type IV collagen. Tubule epithelial cells in culture will be used to study its biosynthesis. Immunohistochemical methods shall be used to supplement the chemical and biochemical methodology. The methodology of 2-D electrophoresis has been developed and will be expanded to study the biosynthesis of crosslinks. Isolation of collagen crosslinks will be aided by 3H-cyanoborohydride.